libxl: convert libxl_domain_destroy to an async op

This change introduces some new structures, and breaks the mutual
dependency that libxl_domain_destroy and libxl__destroy_device_model
had. This is done by checking if the domid passed to
libxl_domain_destroy has a stubdom, and then having the bulk of the
destroy machinery in a separate function (libxl__destroy_domid) that
doesn't check for stubdom presence, since we check for it in the upper
level function. The reason behind this change is the need to use
structures for ao operations, and it was impossible to have two
different self-referencing structs.

All uses of libxl_domain_destroy have been changed, and either
replaced by the new libxl_domain_destroy ao function or by the
internal libxl__domain_destroy that can be used inside an already
running ao.

Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

1 files changed, 40 insertions, 45 deletions

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index dadad76108..6a041f96b9 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -694,6 +694,10 @@ static void spawn_stubdom_pvqemu_cb(libxl__egc *egc,
                                 libxl__dm_spawn_state *stubdom_dmss,
                                 int rc);
 
+static void spaw_stubdom_pvqemu_destroy_cb(libxl__egc *egc,
+                                           libxl__destroy_domid_state *dis,
+                                           int rc);
+
 void libxl__spawn_stub_dm(libxl__egc *egc, libxl__stub_dm_spawn_state *sdss)
 {
     STATE_AO_GC(sdss->dm.spawn.ao);
@@ -914,12 +918,31 @@ static void spawn_stubdom_pvqemu_cb(libxl__egc *egc,
 
  out:
     if (rc) {
-        if (dm_domid)
-            libxl_domain_destroy(CTX, dm_domid);
+        if (dm_domid) {
+            sdss->dis.ao = ao;
+            sdss->dis.domid = dm_domid;
+            sdss->dis.callback = spaw_stubdom_pvqemu_destroy_cb;
+            libxl__destroy_domid(egc, &sdss->dis);
+            return;
+        }
     }
     sdss->callback(egc, &sdss->dm, rc);
 }
 
+static void spaw_stubdom_pvqemu_destroy_cb(libxl__egc *egc,
+                                           libxl__destroy_domid_state *dis,
+                                           int rc)
+{
+    libxl__stub_dm_spawn_state *sdss = CONTAINER_OF(dis, *sdss, dis);
+    STATE_AO_GC(sdss->dis.ao);
+
+    if (rc)
+        LOG(ERROR, "destruction of domain %u after failed creation failed",
+                   sdss->pvqemu.guest_domid);
+
+    sdss->callback(egc, &sdss->dm, rc);
+}
+
 /* callbacks passed to libxl__spawn_spawn */
 static void device_model_confirm(libxl__egc *egc, libxl__spawn_state *spawn,
                                  const char *xsdata);
@@ -1115,55 +1138,27 @@ static void device_model_spawn_outcome(libxl__egc *egc,
 
 int libxl__destroy_device_model(libxl__gc *gc, uint32_t domid)
 {
-    libxl_ctx *ctx = libxl__gc_owner(gc);
     char *pid;
     int ret;
 
     pid = libxl__xs_read(gc, XBT_NULL, libxl__sprintf(gc, "/local/domain/%d/image/device-model-pid", domid));
-    if (!pid) {
-        int stubdomid = libxl_get_stubdom_id(ctx, domid);
-        const char *savefile;
-
-        if (!stubdomid) {
-            LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "Couldn't find device model's pid");
-            ret = ERROR_INVAL;
-            goto out;
-        }
-        LIBXL__LOG(ctx, LIBXL__LOG_DEBUG, "Device model is a stubdom, domid=%d", stubdomid);
-        ret = libxl_domain_destroy(ctx, stubdomid);
-        if (ret)
-            goto out;
-
-        savefile = libxl__device_model_savefile(gc, domid);
-        ret = unlink(savefile);
-        /*
-         * On suspend libxl__domain_save_device_model will have already
-         * unlinked the save file.
-         */
-        if (ret && errno == ENOENT) ret = 0;
-        if (ret) {
-            LIBXL__LOG_ERRNO(ctx, XTL_ERROR,
-                             "failed to remove device-model savefile %s\n",
-                             savefile);
-            goto out;
-        }
+    if (!pid || !atoi(pid)) {
+        LOG(ERROR, "could not find device-model's pid for dom %u", domid);
+        ret = ERROR_FAIL;
+        goto out;
+    }
+    ret = kill(atoi(pid), SIGHUP);
+    if (ret < 0 && errno == ESRCH) {
+        LOG(ERROR, "Device Model already exited");
+        ret = 0;
+    } else if (ret == 0) {
+        LOG(DEBUG, "Device Model signaled");
+        ret = 0;
     } else {
-        ret = kill(atoi(pid), SIGHUP);
-        if (ret < 0 && errno == ESRCH) {
-            LIBXL__LOG(ctx, LIBXL__LOG_DEBUG, "Device Model already exited");
-            ret = 0;
-        } else if (ret == 0) {
-            LIBXL__LOG(ctx, LIBXL__LOG_DEBUG, "Device Model signaled");
-            ret = 0;
-        } else {
-            LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "failed to kill Device Model [%d]",
-                    atoi(pid));
-            ret = ERROR_FAIL;
-            goto out;
-        }
+        LOGE(ERROR, "failed to kill Device Model [%d]", atoi(pid));
+        ret = ERROR_FAIL;
+        goto out;
     }
-    xs_rm(ctx->xsh, XBT_NULL, libxl__sprintf(gc, "/local/domain/0/device-model/%d", domid));
-    xs_rm(ctx->xsh, XBT_NULL, libxl__sprintf(gc, "/local/domain/%d/hvmloader", domid));
 
 out:
     return ret;